Catalytic 1,2-Regioselective Dearomatization of N-Heteroaromatics via a Hydroboration

Heng Liu, Maxim Khononov, Moris S. Eisen*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

26 Scopus citations

Abstract

The thorium methyl and hydride complex (C5Me5)2ThMe2 and [(C5Me5)2Th(H)(μ-H)]2 catalyzed highly 1,2-regioselective dearomatization of pyridines via a hydroboration process is reported herein. Twelve different kinds of meta- and para-substituted pyridines are applicable to this reaction, giving the corresponding N-boryl-1,2-dihydropyridine products in high yields. Other N-heteroaromatic compounds, such as benzo-fused N-heterocycles, pyrazines, pyrimidines, 1,3,5-triazine, and benzothiazole, were also found to be hydroborated with high chemoselectivity. Kinetics including isotope effect studies revealed a first-order dependence on the concentration of catalyst, pyridine, and pinacolborane, with release of the dearomatized final product as the rate-determining step. A plausible mechanism is proposed on the basis of stoichiometric reactions and kinetic studies.

Original languageEnglish
Pages (from-to)3673-3677
Number of pages5
JournalACS Catalysis
Volume8
Issue number4
DOIs
StatePublished - 6 Apr 2018
Externally publishedYes

Keywords

  • 1,2-regioselective
  • dearomatization
  • N-heteroaromatic
  • pyridine
  • thorium

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